Installation of manure-based digester systems at farms in the United States has been in  process since the late 1970s, however the industry is still in its infancy in many ways. Although digester system technologies for capturing and using biogas have been well proven in the United States and around the world, the policies and business models necessary to make these projects viable in most states do not exist. Still, there continues to be growing interest and support in advancing widespread adoption of digesters, especially through the leadership of the dairy sector.

Lack of capital and antiquated energy policies continue to be the two main stumbling blocks to realizing the broad suite of benefits that manure-based digester systems could achieve — local, renewable energy; revenue diversity for farmers and economic growth; greenhouse gas reductions; enhanced environmental protection; and alternative management options for other organic waste streams. Only through coordination between the private, public and NGO (nongovernmental organization) sectors will we be able to see this market grow into a multibillion dollar opportunity.

State Of The Industry

Based on statistics from AgSTAR’s National Digester Database, 176 manure-based anaerobic digestion systems were operating in the United States by the end of 2011, which includes systems that codigest manure and other organic wastes (but not systems that digest wastewater treatment plant (WWTP) biosolids or industrial wastewaters). The number of new anaerobic digesters installed each year remains steady at approximately 16 systems (Figure 1). Almost half of the new projects that became operational in 2011 were complete mix designs, with mixed plug flow designs composing another 40 percent. The remainder of the systems includes covered lagoons, as well as attached growth and induced blanket reactors (Figure 2).

In 2011, the amount of energy produced by digesters —541 million kilowatt-hours (kWh) — was enough to supply more than 36,000 average American homes for a year. The majority of the energy produced is in the form of electricity in combined heat and power systems that also capture heat for useful purposes. Other operations use the gas as a boiler fuel,upgrade it for injection into natural gas pipelines, or simply flare it for odor control.

Direct and indirect greenhouse gas reductions through capture and destruction of methane in anaerobic digesters were significant in 2011. Direct reduction of 55,000 metric tons of methane emissions, or 1.2 million metric tons carbon dioxide equivalent (CO2e), plus an additional reduction of 301,000 metric tons of CO2e avoided by displacing fossil fuels with captured methane are equivalent to removing almost 300,000 passenger vehicles from the road or reducing oil consumption by almost 3.5 million barrels.

Trends

Trends in 2011 saw approaches other than the traditional farm-based, manure-only systems emerging. For example, approximately 30 percent of systems are adding other organic feedstocks (e.g., food waste, agriculture waste, cheese whey). There is also significant growth in the number of third-party owned and operated systems. While the industry continues to reach less than two percent of the market for manure-based digesters, if the potential for codigestion of other organic waste streams (e.g., food production and processing by-products, agricultural wastes, source-separated organics) with manure is considered, the opportunity is greater.

Electric generating capacity of digester systems has been increasing since 2003. Average project capacities have grown from 125 kW to 454 kW. A number of factors have contributed to this trend, including increasing use of additional feedstocks and the emergence of larger farm and centralized systems. Since 2006, 10 systems have been installed with capacities greater than 1 megawatt (MW) and 7 more have capacities over 2 MW. And a brand new record was set in 2011 — the digester system with the largest electric generating capacity in the U.S. based solely on dairy manure became operational in Idaho and has the potential to create 4.5 MW of energy.

Overcoming Obstacles

The manure-based digester industry has been facing hurdles since the 1970s, when several manure-based digesters were installed, only to fail due to lack of proper maintenance, poor operating practices, or because of financial issues. It was always recognized that the technology was sound, and industry knew that digesters could succeed as long as these problems were addressed. The majority of digesters installed in recent years continue to succeed. From determining true project costs and developing a sound business plan to emphasizing the importance of quality equipment, sampling feedstocks, and performing the required maintenance on schedule, anaerobic digesters today are recognized as part of sophisticated biogas recovery systems that are an integral part of the livestock operation and interrelated to livestock care and crop management.

Traditional manure-based digesters in the 1970s focused on creation of renewable energy — mainly in the form of electricity — to offset a farm’s needs. In the following years, creation of renewable portfolio standards in many states allowed digester operators to command higher prices for the kilowatt-hours produced by generating renewable electricity credits that could be sold to utilities. As natural gas prices rose, other projects were developed to upgrade the biogas to pipeline quality to sell at a premium.

However, markets changed, utilities met the required standards (often through the acquisition of “cheaper” renewable power from wind and solar projects), and prices fell, meaning that projects can no longer be financially justified solely from the viewpoint of electricity generation. Throughout this time, energy policy has remained largely unchanged. Besides the fact that tariffs/rates, net metering rules and interconnection policies vary widely throughout the country, most of the policies place a great burden on the project developer, rather than the utility. However, some utilities shine as leaders in the movement to supply farm-based renewable energy, whether by offering progressive rates for the electricity generated as the Cow Power Program of Central Vermont Public Service does, or by modifying net metering policies to allow for remote net metering as in New York.

Increasing numbers of anaerobic digesters and use of innovative models or cosubstrates raise permitting and regulatory issues for regulators unacquainted with the technology and/or where several agencies must interact to determine jurisdiction over the project. Increasingly, air emissions from energy generation equipment are being scrutinized, especially in regions with nonattainment status. As these issues arise more frequently, relatively simple activities, like publishing case studies or best practices of successful permitting examples, such as those in Michigan and Washington, could spur cooperation among agencies in other states.

Financing continues to be the greatest hurdle facing digester systems. Developers must provide initial capital and public funding is decreasing. Long-term viability of the industry requires projects to be able to be implemented without grant subsidies. To address this, developers are monetizing the on-farm benefits, such as decreased transportation costs for fertilizer that can now be pumped to fields, and considering all potential revenue streams including tipping fees (especially from food waste and other organics as regulators seek to divert those wastes from landfills), carbon credits (especially as California’s market is put into practice), Renewable Energy Certificates and emerging nutrient credits.

Moving past electricity, projects like the one at Fair Oaks Farms in Indiana (see “Indiana Dairy Fueling Fleet With Renewable Natural Gas,” September 2011) are finding ways to offset costly vehicle fuel through production of compressed natural gas (CNG) from their biogas. Groups continue to seek ways to reduce the cost of upgrading biogas to biomethane that can be injected into gas pipelines. Even finding efficient ways to store biogas so that it can be held and sold at peak periods would improve the bottom line of many projects.

New markets for digestate are also being explored. While use of digestate as bedding and fertilizer on the farm offsets costs, there is often leftover material. Profit can be realized by converting the material into consumer products for anything from soil amendment or peat moss replacement to filler in particle board or plant pots. Some digesters are even becoming agrotourist sites, charging nominal fees to learn about the system.

Models To Move Forward

After successfully tackling traditional hurdles, the digester industry is proactively addressing current challenges in a variety of ways. Emergence of third party build-own-operate models of digester systems, where producers often provide land and feedstock to a digester but another company manages the daily operations, helps maximize gas production and revenue by letting each party concentrate on the part of the system they specialize in — whether it’s getting manure from healthy cows or monitoring gas production and ensuring that required maintenance is performed on schedule.

Developers also are working to increase the number of digesters in less traditional settings. More specialized small-scale systems are being built with refinements that enable the capital costs to decrease. Other business models also are being used, such as building multiple systems on small farms in close proximity to each other at one time, allowing materials to be purchased in bulk and the savings passed on, or bringing in additional organic sources for codigestion resulting in a larger system that can capitalize on better economies of scale.

Centralized systems continue to be a challenge due to complexity and price, especially as transport costs continue rising. Some communities are looking at ways that the public sector can be involved when water quality or wide-spread nutrient concerns are at stake. As municipalities recognize the benefits that digesters provide to a community, more may follow Dane County, Wisconsin’s example and shepherd systems into existence. (See this issue’s “Community Sustainability” feature on the Dane County community digester project.) Public sector involvement can open doors to additional sources of funding, such as municipal infrastructure bonds, decrease the costs and hurdles of permitting, and garner public support for the project. Other groups, such as NGOs, can support centralized projects with creative financing models as well.

Several other trends are emerging that may increase revenue from digester systems and encourage their installation at greater rates. Digester systems are a targeted solution for those promoting energy independence as they can offset a number of different energy sources, from electricity to natural gas to vehicle fuel. Ever-increasing fuel prices could also be a driver for digester implementation as more CNG fueling stations are installed and more vehicles are converted to run on CNG. This could especially benefit municipalities willing to support centralized digester systems that have fleets of vehicles that could capitalize on the fuel. Additionally, organizations outside of utilities that are interested in promoting locally produced green power can look for creative ways to match demand with energy producers like digesters.

Manure-based digesters in the U.S. continue to show steady growth. The industry has come a long way and addressed many challenges, laying necessary groundwork. While hurdles still exist, keeping exponential growth at bay, the industry’s commitment to persistence and innovation, whether in technology or financing, keeps hope alive. As more communities get on board and public knowledge of digester benefits is increased, more systems will be installed. With organizations like the Innovation Center for US Dairy and the American Biogas Council backing digesters, the future can only get brighter.

Source: www.biocycle.net

Allison Costa is Program Manager and Chris Voell is National Program Manager with the U.S. Environmental Protection Agency’s AgSTAR office (www.epa.gov/agstar).

2011 Stats

• 176 digesters in operation

• 15 new digesters brought on line

• 541 million kWh of energy generated

• 1.2 million metric tons of CO2e destroyed

• 301,000 metric tons of CO2e avoided

Source: USEPA AgSTAR

Biogas comes from animal manure, and is perhaps the ultimate win-win energy source, allowing farmers to produce their own electricity and reduce the water contamination, odor pollution, and global warming emissions caused by animal waste.

Biogas is produced when bacteria decompose manure anaerobically — without the presence of oxygen — into a gas mixture composed of about 60 to 70 percent methane. This gas mixture can be used to generate heat, hot water or electricity, and the leftover digested manure can be used as fertilizer, bedding, mulch and potting soil.

In 2011, there were about 180 operational biogas recovery systems on American commercial livestock farms, which produced enough electricity to power the equivalent of 47,000 homes.[1] The EPA’s AgSTAR program reported in 2010 that about 8,000 U.S. farms could support biogas recovery systems, providing about 1,600 megawatts of energy and reducing emissions of global warming pollution by about 1.8 million metric tons of methane — the equivalent of taking 6.5 million cars off the road.

How Biogas Energy Works

Biogas recovery systems have a few main components: a manure collection system, an anaerobic digester, usually a covered lagoon or tank, which stabilizes the manure and optimizes methane production; a biogas handling system that pipes the resulting gas to the device it will fuel, such as a generator; and a storage tank for the remaining discharge.

There are a few types of digesters: Covered anaerobic lagoons are pond-like basins, often earthen, that are covered to retain the biogas. Lagoons are the simplest and most popular biodigesters, but they are limited to warmer climates — colder temperatures can suppress methane production. Plug-flow digesters are long, narrow, heated tanks, often installed partially underground to retain the heat. These units work only with dairy manure. Complete-mix digesters are heated tanks made of reinforced concrete or steel with a mechanical, hydraulic or gas-powered mixing system. They generally require a diluted manure mix, such as manure mixed with process water.

Where Biogas Energy Is Used

Biogas is most commonly used on the farm where it’s produced, mostly for electricity or as boiler fuel for space and water heating. Any excess electricity can often be sold back to the grid.

Large dairy and swine operations have the greatest potential to produce cost-effective biogas. Biogas recovery systems can handle liquid, slurry, or semisolid manure, and these operations can collect and store enough of this manure to produce large amounts of biogas.

AgSTAR, a voluntary program administered jointly by the U.S. Environmental Protection Agency, Department of Agriculture, and Department of Energy, promotes biogas recovery systems at concentrated animal feeding operations (CAFOs) across the country.

A single CAFO can generate as much waste as a small to midsized city, and can affect the water supply and air quality of an area that extends far beyond the operation itself. There is very little government oversight of these operations — the EPA does not have a definitive national list — and they pose very real risks to air and water quality. By capturing manure, biogas recovery systems can drastically reduce or eliminate untreated waste runoff from CAFOs, but in the end, strong environmental protections and government oversight of CAFOs are needed to ensure that the risks of polluted runoff are mitigated.

Because methane is one of the most potent greenhouse gases, farmers who use biodigesters can get paid by carbon offset companies.

How Much Biogas Energy Costs

The profitability of a biogas digester depends on the size of the operation, the method of manure management and local energy costs. According to AgSTAR, biogas recovery can be profitable and most effective at existing operations of at least 500 cows or 2,000 swine. Manure should be collected frequently (at least once a week) in a liquid, slurry or semi-solid state. Any electricity that is not used on-site can usually be sold to the local utility.

Because methane is one of the most potent greenhouse gases — 21 times as powerful as carbon dioxide in trapping heat — farmers who use a biodigestion system can arrange to be paid by a carbon offset company. These firms have emerged in recent years in response to the growing demand from companies and individuals who want to reduce their environmental impact by “offsetting” the emissions they produce in their everyday activities. Carbon offset companies sell “carbon credits” to interested parties, and use the proceeds to pay others to reduce their global warming pollution.

In 2011, biodigesters on U.S. farms produced enough electricity to power the equivalent of 47,000 U.S. homes.

Advantages of Biogas Energy

• Air quality improves significantly because the biodigester reduces the smell of manure, turning its volatile organic compounds (VOCs) into odorless methane and carbon dioxide. Hydrogen sulfide, the source of the “rotten egg” odor, is captured in the biogas and destroyed during combustion.
• Cleaner water is an important benefit: biodigesters reduce bacteria levels in animal waste, which means that any runoff to surface waters will be less harmful. Digesters also reduce biochemical oxygen demand (BOD), a measure of the ability of organic wastes to remove oxygen from water. Aquatic species depend on dissolved oxygen in water for survival, so farms that reduce BOD help protect aquatic ecosystems.
• Greenhouse gas reduction is critical in mitigating climate change. Seven percent of methane emissions in the United States come from livestock and poultry manure, most of which in turn comes from swine and dairy operations. Biodigesters eliminate nearly all methane emissions, and as a renewable source of energy they reduce our reliance on fossil fuels.

Biodigesters have the potential to slash methane emissions by 1.8 million metric tons — the equivalent pollution reduction of taking 6.5 million cars off the road.

What’s Around the Corner for Biogas Energy

• Biodigesters are increasingly popular for a number of reasons, including farmers’ interest in selling carbon credits and utilities’ interest in meeting the renewable portfolio standards that more than 30 states have adopted. A renewable portfolio standard is a government mandate, usually at the state level, for electricity supply companies to produce a specified fraction of their electricity from renewable energy sources. Certified renewable energy generators earn certificates (known as renewable energy credits) for every unit of electricity they produce, and can sell these along with their electricity to supply companies.
• Organic (food and yard) waste biodigestion is now being considered as part of a broader push to keep organic waste out of landfills and capture the energy and ecological benefits of doing so. University of Wisconsin – Oshkosh is piloting the nation’s first dry biodigester, which will convert campus food and yard waste into heat and electricity.
• The USDA Rural Business-Cooperative Service (RBS) is accepting applications for grants and loan guarantees from agricultural producers and rural small businesses that want to purchase renewable energy systems and/or improve their energy efficiency. Eligible systems include anaerobic digesters that use animal waste and other substrates to produce thermal or electrical energy.
• New digesters with gas-fired engines will be subject to emission limits for nitrogen oxides, carbon monoxide, and volatile organic compounds (VOCs). For more information, visit the EPA’s AgSTAR newsroom.
• Congress should limit greenhouse gas emissions (GHG) from large manure management facilities in confined animal feeding operations, or CAFOs. According to the EPA, greenhouse gas emissions from livestock in large CAFOs account for a significant portion of agricultural GHG emissions in the United States.

Source: www.nrdc.org

Green America has started an online petition to hasten AWS’s transition to renewable energy, claiming its servers burn through enough energy to power 600,000 homes each year. It also wants the world’s biggest public cloud provider to open up about its green energy targets, starting by issuing an annual sustainability report and submitting annual energy data to the Carbon Disclosure Project.

The environmental group pointed out AWS is being outperformed by rivals like Google and Microsoft when it comes to renewable energy.“Unlike Google, Facebook, and Microsoft, Amazon has disclosed virtually no information about its energy use and its impacts on the climate,” the group said.

“While Google and Apple have committed to running on 100 per cent renewables and are happy to flaunt their progress to the public, Amazon has done little more than state a goal of moving to renewables, with no plan or timeline for doing so.”

The online campaign follows an open letter signed by 19 AWS customers last month, calling on the company to commit to transparency over its energy usage, carbon footprint, and renewable energy goals. In the letter, posted online by the Wall Street Journal, firms including Hootsuite, Tumblr and Upworthy wrote: “[AWS should] provide clarity on AWS’s principles for how it defines renewable energy, and what type of options it will prefer moving forward, so that we and our customers and users can have confidence in the integrity of AWS’s commitment.”

The cloud company  recently announced it is helping build a 150 megawatt wind farm in Indiana to provide renewable electricity for its datacentres, winning Greenpeace’s approval.

But for servers in its US East region, it also uses electricity that is up to 97 per cent coal-powered, according to Green America.

Jeff Barr, AWS’s cloud chief, said in a blog post last week that AWS customers use 77 per cent fewer servers and 84 per cent less power than they would operating their own datacentres.

He added: “AWS remains focused on working towards our long-term commitment to 100% renewable energy usage.

“The AWS global infrastructure is powered by approximately 25% renewable energy today, and that we expect to reach 40% by the end of 2016.

“We have several additional developments planned in the next 12 -18 months to help us get there and encourage our customers to check back on our sustainability page often to watch our progress‎.”

Source: www.cloudpro.co.uk

Google will convert an old coal-fired power plant in rural Alabama into a data centre powered by renewable power, expanding the company’s move into the energy world.

The technology giant said on Wednesday that it would open its 14th data centre inside the grounds of the old coal plant, and had reached a deal with the Tennessee Valley Authority, the region’s power company, to supply the project with renewable sources of electricity. With the coal plant rehab, Google solidifies a reputation among tech companies for promoting clean energy.

“It’s very important symbolism to take an old coal plant that is a relic of the old energy system and convert it into a data centre that will be powered by renewable energy,” said David Pomerantz, climate and energy campaigner for Greenpeace.

Michael Terrell, who leads energy market strategy for Google’s infrastructure team, said the company saw clear benefits in taking over the old coal facility. “There is an enormous opportunity when you take over the infrastructure that is there – the transmissions lines and the water intakes – and use that to power a data centre that is powered by renewable energy,” he said.

Outside utilities, Google claims to be the largest user of renewable energy in the US. The company says it uses 1.5% of wind power capacity in the US, and has plans to bring in more alternatives over the next year.

However, the company overall still treads with a relatively heavy carbon footprint compared to Apple.

About 46% of Google’s data centers are powered by renewable energy. Apple’s in contrast are powered 100% by clean energy, according to Greenpeace. Google is committed to going 100% renewable, but has no target date.

Google went into the renewable energy business earlier with data centres in Iowa and Oklahoma. However, the company still has three data centres in south-eastern states which rely heavily on coal and nuclear power, North Carolina, South Carolina, and Georgia.

Pomerantz said the move into Alabama was so encouraging because it challenged that dominance.

The company said it would be working directly with TVA to bring more wind power into the grid. “We see a lot of value in redeveloping big industrial sites like this. There is a lot of electric and other infrastructure that we can re-use,” Matt Kalman, a Google spokesman said in an email.

Google is also rehabbing old industrial facilities overseas. The company repurposed an old paper mill in Finland for use of a data centre. It has already done a solar project in South Africa, and is scouting out other ways of producing clean energy cheaply.

The Alabama power plant has been generating power since 1952, but was slated to wind down later this year, in part because of incoming environmental regulations, the TVA said on its website.

Source: www.theguardian.com

Facebook is building a new data center in Fort Worth, Texas, that will be powered entirely by renewable energy. The company will invest at least US$500 million in the 110-acre site, which is expected to come online late next year.

The new location will be the social-networking giant’s fifth such facility, joining existing data centers in Altoona, Iowa; Prineville, Oregon; Forest City, North Carolina; and Luleå, Sweden. It will feature equipment based on the latest in Facebook’s Open Compute Project data-center hardware designs, it said.

For sustainability, the Fort Worth data center will be cooled using outdoor air rather than energy-intensive air conditioners, thanks to technology it pioneered in its Oregon location. Those designs are now offered through the Open Compute Project.

It will also be powered entirely by renewable energy as a result of a new, 200-megawatt wind project now under construction on a 17,000-acre site in nearby Clay County. Facebook has collaborated on that project with Citigroup Energy, Alterra Power Corporation and Starwood Energy Group; it expects the new source to begin delivering clean energy to the grid by 2016.

Facebook says its infrastructure efficiency efforts have helped it save more than $2 billion over the last three years. The carbon impact of one person’s use of Facebook for an entire year, meanwhile, is now equivalent to that of a medium latte, Facebook said Tuesday.

The company aims to power its data centers with 50 percent renewable energy by the end of 2018, according to Jay Parikh, its vice president of engineering.

“Facebook’s new goal of using 50 percent renewable energy and commitment to powering its Texas data center with clean wind power demonstrates the kind of transparency needed to show that it is making steady progress toward its goal of using 100 percent renewable energy,” David Pomerantz, senior climate and energy campaigner with Greenpeace, said in a statement.

In sharp contrast, Pomerantz added, is Amazon Web Services, which “has failed to explain how it will power its newly announced data centers in Ohio and India, despite the company’s commitment to use 100 percent renewable energy.”

Amazon didn’t immediately respond to a request for comment.

Source: www.itworld.com